摘要
以超临界CO2为工质,试验研究其在内凸管内的对流传热特性,并与相同工况下的光滑管试验作对比,由此获取内凸管结构对超临界CO2传热过程的强化效果。试验参数范围:系统压力7.6~8.4 MPa、质量流速400~700 kg/(m2·s)、热流密度100~200 kW/m2、流体温度18~64℃和雷诺数1.2×104~4.9×104。对比了相同工况下内凸管与光滑管换热过程的努赛尔数及阻力系数,并采用综合性能指标PEC来定量评价内凸管传热强化效果。结果显示,内凸管结构能以较小的阻力代价获取较高的传热系数增幅,其综合性能指标PEC为1.24~1.52,表明内凸管能有效强化超临界CO2的对流传热。根据试验数据,拟合了适用于该文内凸管的传热关联式,预测误差小于±10%。
The heat transfer enhancement technology for supercritical CO2 is of great significance to promote the technical development of new energy conversion systems such as supercritical CO2 Brayton cycle.In this study,the convective heat transfer of supercritical CO2 in an inner convex tube is experimentally carried out.The results are compared to those obtained in smooth tube under the same working conditions in order to evaluate the heat transfer enhancement performance of inner convex tube.The operating parameters ranges are as follows:system pressure p is from 7.6 to 8.4 MPa,mass flux G is from 400 to 700 kg/(m2·s),heat flux q is from 100 to 200 kW/m2,fluid temperature Tbis from 18 to 64℃and Reynolds number Re is from 1.2×104 to 4.9×104.The Nusselt numbers and the resistance factors for inner convex tube and smooth tube are compared under same working conditions,and a comprehensive performance index PEC(Performance Evaluation Criterion)is employed to quantitatively evaluate the heat transfer enhancement performance of the inner convex tube.The results show that the inner convex tube can improve heat transfer coefficient obviously with moderate resistance cost,and its PEC is in the range from 1.24 to 1.52,indicating that inner convex tube can effectively enhance convective heat transfer of supercritical CO2.According to the experimental data,a heat transfer correlation for the present convex tube is developed,and the prediction error is less than±10%.
作者
颜建国
朱凤岭
郭鹏程
白晨光
马健博
Yan Jianguo;Zhu Fengling;Guo Pengcheng;Bai Chenguang;Ma Jianbo(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi’an University of Technology,Xi'an 710048,China;China Qiyuan Engineering Corporation,Xi'an 71OO18,China)
出处
《太阳能学报》
EI
CAS
CSCD
北大核心
2020年第7期244-250,共7页
Acta Energiae Solaris Sinica
基金
国家自然科学基金(51839010)
陕西省重点研发计划(2017ZDXM-GY-081)
中国博士后科学基金(2018M633546)
陕西省自然科学基础研究计划(2019JQ-185)。
关键词
超临界流体
对流传热
流动阻力
关联式
传热强化
supercritical fluids
heat convection
pressure drop
empirical correlation
heat transfer enhancement
